High conductivity of the interconnects or the metal layers of an integrated circuit is important for the efficient operation of such a circuit, particularly at submicron technologies. In previous integrated circuits, aluminum has been utilized to provide the interconnect for the device. However, as standards for speed have increased, i.e., smaller and smaller process technologies (0.18 .mu.m and lower), other metals have been used. In a preferred embodiment, high conductivity metal such as copper, gold and platinum have been used as the interconnect to enhance the speed of the device.
High conductivity interconnects in particular are highly desirable for advanced wirings in logic technology. However, high conductivity metals such as copper, gold and platinum have very high diffusivity through several dielectrics. This high diffusivity is a problem because in a typical processing of the device, the metal will get sputtered from a bottom metal layer onto the sidewall of the device. This elemental layer then has to be removed in order to prevent any diffusion from the walls of the via to minimize poisoning of the junction. Conventional chemical processes employed to remove high conductivity metal from the sidewall of the dielelectric material will also remove/attack high conductivity metal at the base of the via. Accordingly, although the high conductivity interconnects increase the overall performance of the device, they also provide challenges in manufacturing the device.
What is needed, therefore, is a system and method which minimizes the poisoning of associated with high conductivity metals that also have high diffusivity. The system and method should be easy to implement and cost effective. The system and method should also be easily adaptable utilizing conventional processing techniques.
The present invention addresses such a need.